Top speed mag for a 2012 CBR 250R not RR my point was to show that even a 4 stroke with almost double the capacity is still behind the eight ball compaired to a 150 2 stroke. or even if we add in the RR it still proves that the 150cc 2 stroke is not very far behind the performance curve of the top dog 250 4 stroke ....its that model of 2 stroke that holds the world record in the 175 class at over 130 mph

Chris..... please point me to any 150cc 4 stroke that was/is a production model and can still be purchased (new or second hand) that has exceptionally more performance than these 4 strokes? Again the point is to expose the vast power difference between 2 production models that represent the top of the performance ladder, its chalk and cheese.

Guys I admire that you want to race these small capacity 2 strokes it really does make racing afffordable and bang for buck you cannot beat a 2 stroke, I hope you all exceed in your dreams of a record Alas if I were to campain a 4 against a 2 in this class my hopes of a record would be just that ...a dream
cheers
gary

30HP is attainable out of a Honda CRF150R single motocross WATER COOLED engine. They're a multivalve thing. A bloke was running one of these in the Motolite class with the PCRA. Nobody could catch him. Interestingly, in that class, they put 150cc water cooled 4 strokes against 185cc air cooled 4 strokes, 100cc air cooled two strokes and 85cc water cooled two strokes. At first the 4 stroke boys still complained at how they couldn't possible match the two strokes. They wanted double the capacity of the smokers. Then within a couple of years the smokers couldn't catch the 4 strokes anymore.

Even with that capacity advantage, the air cooled bikes have no chance of being anywhere near the front. This isn't speculation. This is years of actual race results with these engines against each other.

hawkwind wrote:Its time to look at this disadvantage and see if placing the smokers up 2 capacity classes will level the playing field ..... ie. 500cc goes to 1000cc 250 to 500 etc
comments anyone ?

Then you say

Firstly Im not advocating or seeking any rule changes ...just after some lively discussion about 4stroke vs 2 stroke .....reason I started this thread is while looking at the class records where 2 strokes are going head to head with 4 strokes the difference is quite pronounced in speeds..... while i admit there could be many reasons for this; to my mind the largest would have to be the inherent advantage of two power strokes to one ....and as pointed out doubling the rpm of the 4 compared to the 2 in theory would negate this advantage in real life that's mostly not achievable.
Cheers
Gary

Why are would you possibly want to have a lively debate without it actually achieving something? Especially when the off shoot of this might be, that someone does push for 2 Strokes to actually be penalised Gary?

Your oversimplified formula X 2 is seriously flawed, just like penalising Rotaries was, and that was what my ridiculous formula was alluding to.

It might apply to 250s. If you applied it to 125s you would then have a

or a 750cc 2 stroke goes into the 1650cc Class. So a 1970's 2 Stroke and a ZX14R would be in the same class???

Try a 1976 RD 400 running against a BMW S 1000RR. WTF

THAT'S A GREAT EQUALISING FORMULA, SO EASY simply X 2

I run a 250 2 stroke because it has a power advantage in 250cc class, but if someone had enough money to run a late Model Honda RS ( my choice but can't afford it) or Yam TZ 250, then my RGV based bike would not have a look in, that's Motorsport.

Honestly Gary, if you seriously wanted to set a record in the 1000cc classes would you run a new Triumph Bonneville or a Suzuki GSX-R?

Would you then insist that the GSX-Rs or R1s are penalised because the Twin you have chosen as a Bike to set Records on could not possibly do it?

If it is the "big issue" that you make it out to be Gary, I am happy to support having separate 2 Stroke/4 Stroke Classes as the simplest and fairest way to address this concern that you, Gary, have raised?

If you are simply trying to stir things up and think it's a bit of a laugh, well I'm always up for a laugh (see my Formula). That is unless of course it clearly starts to single out Members that compete legally under the existing Class structure and then suggest we get "penalised' for doing so.

Actaully I was not going to put the Rule Submission in that I wrote up, but I think I will now, just to make sure you are not disadvantaged by my weapon of choice.

[quote][If you are simply trying to stir things up and think it's a bit of a laugh, well I'm always up for a laugh (see my Formula). That is unless of course it clearly starts to single out Members that compete legally under the existing Class structure and then suggest we get "penalised' for doing so./quote]

Oh dear it seems I have put some noses out of joint I cast my line and caught a few let me say sorry if you were taking this seriously................I do have a small toy by the name of Suzuki 150R ....its an underbone ( a step through to aussies) I was going to give it a run but now It will become a pit bike.

Your advantage over 4 strokes will remain unchallenged.......though it is very real.

Thanks Chris for the info .......I have no idea about what you dirt blokes race ........ never really been interested in chook chasers.... from what you are saying I better check out your weapons.

Pete I have been doing this landspeed stuff for a little while.....well its time I retired to the shed to see if I can make my slow old 1000cc racer a little bit faster than those BMW's

The beers are on me ( one round only) when we use the big white dyno next.

hawkwind wrote:
Thanks Chris for the info .......I have no idea about what you dirt blokes race ........ never really been interested in chook chasers.... from what you are saying I better check out your weapons.

The PCRA Motolite and Superlite classes had quite a few motocross and enduro engines in them (YZ85, CRF150R, DT100, YZ100 etc) but we weren't racing on dirt. It was tar circuit racing (Wakefield, Oran Park, Eastern Creek etc.)

The engine capacity restrictions did even it out at first but the four strokes very quickly become the tool of choice because the 2 strokes had already reached the limit of their development and were becoming fragile (explodey goodness). The four strokes were producing more horsepower, more reliably.

But the air cooled engines (185cc 4T & 100cc 2T) got left behind very early on even with their extra engine capacity advantage.

How much of the 2 stroke "advantage" on the circuit tracks etc is due to power to weight ratios that become irrelevant on the salt where a slower accelleration rate in general has no impact on terminal speed

Well Gary, ya certainly had me going. You will find that most of us 2 smokers are a very passionate bunch. There has been pretty well no development on the 2 stroke front for 10 or more years, its just rehashing old ideas and finding ways to make old ideas work better. I think the only 4 stroker with anywhere near as much passion in this class would be Tiny. Imagine the smelly 2 stroke he could build if he put his mind to it? And the supercharged-turboed postie bike of course. We just need to convince them to come over to the smelly side.

RGV wrote: Imagine the smelly 2 stroke he could build if he put his mind to it? We just need to convince them to come over to the smelly side.

Ill buy the second round.

Dave

It's NEVER gonna happen !,
I has the misfortune to ride with a full house Yam YDS5 250, and a Mach 111 kwacka in the late '60's, the Yam had unmuffled expansion chambers, Wal Philips "fuel injectors". and not only made the windows shake while it took off from the main drag (no power under 8.000 rpm) it HURT any ears within a 100 yrds, then theres that,,,SMELL
Tiny